I have a 2016 Vegas . When I read the Guage on the propane tank outside it has not moved from the original position when I brought my Vegas 5 months ago. When I check the monitor panel inside the coach, it shows the LP level at 3/4 full. I have had the propane on numerous times . Is the inside monitor reading correct and does it over ride the one on the propane tank

Here are my thoughts and three cents on your question. If you are only periodically using the propane for the refrigerator and a bit of stove cooking, water heater and stove top cooking, you are using very little of the propane. The furnace heater will use it at a faster rate which you might notice. Sounds like all is well.

I am going to assume (possible mistake) that your tank gauge is reading full when the monitor panel is reading 3/4.

Something to keep in mind is a propane tank can only be filled to 80 percent capacity to allow for expansion. The tank gauges on my coach and my prior Class C were calibrated to read full when the tank was filled to 80 percent. With that said, your inside panel panel may not be calibrated to take the 20 percent factor into consideration.

My prior Class C had a procedure for calibrating the monitor panel indicators but I haven't seen that procedure for this coach, and in all honesty, I haven't thought about it until I read this thread. I do believe, however, the procedure will be very similar.

Here is a link to a video and info on how to calibrate the monitors at the panel. It is being done on a Newmar but again the procedure should be about the same.

For LPG the calibration should be done immediately following a tank fill up.

Very much depends on what you are using the propane for...
I've gone 3 months with propane to spare in Florida winter - used for cooking (stove, oven, outside grill) and heat (limited need)...
Water Heater and Fridge were on Electric...

The next winter I used 2 tanks for same time frame - primary difference was more need for heat!

In colder climates, the heat will drink propane quickly...

The tank gauge wins the battle if there is a disagreement with the panel. Even full, the tank gauge reads around 3/4 - with the space for expansion (look at where the valve is that indicates full at the pump...)